The present invention relates to an electric drill, and more particularly to an electric drill which has a rear compartment for accommodating a set of grinding means that occupies only small room and is ready for use at any time.
FIG. 1 illustrates a conventional electric drill 1, the front end of which securely holds and clamps a drill bit 11 for pressing and drilling a piece of work. Since the drill bit 11 always works under high speed and higher pressure, its head end, after long period of use, tends to have worn lip angle, lip clearance angle, and cutting edges. At this point, it is necessary to grind the drill bit 11 with a grinding means 13 having a grinding wheel 12. Most of the conventional grinding means 13 would require a support 14 or a simple working table. In a more complete grinding means 13, a jig 15 is provided to facilitate an grinding operator to actually control all working angles needed by a grind drill 11. It is therefore desirable to have the grinding means 13 provided at the site where electric drills 1 are required to drill holes, or, standard or ground drill bits 11 must be prepared in advance so that they are ready to substitute for those worn ones without delaying working progress. However, since a complete grinding means 13 is expensive in cost and is usually bulk in volume and not easy to move, it is usually provided only in larger working sites, such as plants. For working sites other than plants, ground drill bits in different sizes are carried based on the operator's experience and memory to meet incidental requirement lest the work under going should stop.
In view of the existing disadvantages and inconvenience that a worn drill bit can not be ground anywhere at any time due to the fact an electric drill and a grinding means 13 are separately provided, it is therefore tried by the inventor to develop an electric drill completed with a set of grinding equipments.